1. Field of the Invention
The present invention relates to an optical disc recording apparatus which records and reproduces information to and from an erasable optical disc, such as a CD-R media or a CD-RW media.
2. Description of the Related Art
The minimum reproducible unit of data that can be recorded onto the recording area of a read only optical disc (e.g. CD), a recording optical disc (e.g. CD-R), or an erasable optical disc (e.g. CD-RW) is called a "BLOCK". Each block is made up of between 2048 bytes and 2352 bytes of data. The minimum recording unit of data for an optical disc (e.g. CD-R, CD-RW) is called a "packet". The packet comprises at least one user data block to reproduce data, five linking blocks (one link block and four Run-In blocks) before the user data block and two linking blocks (two Run-Out blocks) behind the user data block. The linking blocks are necessary to link the packets to each other when recording data on the optical disc, and do not include any user data.
The recording format of a CD-R or CD-RW optical disc is prescribed in the Orange Book, an industry standard. The Orange Book rules dictate that data sectors which are not consecutively written require lengthy lead-in and lead-out sectors such as Link, Run-In, and Run-Out sectors. These sectors are necessary to enable optical disc drives to synchronize to the data on the optical media. This is because the laser beam must be repositioned each time a new writing session is started, and known optical disc drive positional controls are not sufficiently accurate to position a laser beam at the exact end point of previously written data.
There are at least two methods to record data onto a CD-R or CD-RW disc, the Track-at-Once method and the Packet Write Method. The Track-at-Once method records one track with one packet. The user data blocks in the track are recorded sequentially and thus, there are no linking blocks between the user data blocks. The Track-at-Once method is capable of recording a maximum of 99 tracks on the optical disc. In the Track-at-Once method, the start address and end address are recorded in a different area as a Table Of Contents (TOC). In other words, in the Track-at Once method, the optical disc drive must write the entire disc or track in a single writing session.
The Packet Write Method, on the other hand, divides the track into a plurality of packets and records data by packet unit. The user data in one track exists independently and is separated from other user data blocks by linking blocks. There are two different ways to record on an optical disc using the Packet Write Method, a fixed length Packet Write Method and a variable length Packet Write Method. The fixed length Packet Write Method records material by fixing the size of the packet by limiting the number of user data blocks of the user data in the packet. Thus, the packet length or packet size in the track is a predetermined size. The variable length Packet Write Method records material with a variable packet length in the track.
When using the Packet Write Method, a physical address is assigned to each block in the optical disc with the first physical address corresponding to zero. When accessing the physical address, it is possible to access the physical address indirectly by converting the logical address to the physical address.
In the variable length Packet Write Method, the physical address and the logical address are linearly related with a logical address being assigned for each user data block. In the variable length Packet Write Method, a logical address is also assigned to each linking block which can not be accessed. Therefore, a logical address exists in the variable length Packet Write Method that can not be accessed.
In the fixed length Packet Write Method, a logical address is assigned only to the user data blocks. The first user data block of the track corresponds to a logical address. The first logical address is assigned to the user data block corresponding to the first user data block and the logical address skips the linking block. The next logical address is assigned to the second user data block. Accordingly, in the fixed length Packet Write Method the logical address is continuous and the information recorded on the optical disc can be reproduced without knowledge of the contents of the packet.
However, all packet write methods require that the minimum recording unit of data be recorded at once. Thus, it is impossible to divide up the data contained in one packet and write that data contained in the one packet in many consecutive recordings. If one divides the data, it is necessary to add a linking block to the user data blocks in accordance with the linking rules. In this situation, the data is thus no longer one packet but a plurality of packets that must have linking blocks between the user data blocks. Otherwise the data without the linking blocks will not be able to be reproduced.
Data is not always recorded successively to previously recorded data on the optical disc. For example, if dust obscures the data recording portion of an optical disc, or a vibration is produced during the recording of the data, the data recording for the optical disc may fail, causing a recording error. If a data error occurs, the data recorded on the packet can not be reproduced; however, the data may be rewritten on the disc.
A conventional optical disc recording apparatus is shown in Japanese unexamined patent publication (KOKAI) No 7-235133. The recording apparatus records data onto a write-once optical disc to enable the previous recording to be read if the previous recording was incomplete. The conventional optical disc recording apparatus also enables additional data to be recorded onto the write-once optical disc following the incomplete recording.
However, in the conventional optical disc recording apparatus, it is impossible to reproduce the data from a packet which was not recorded onto the optical disc (e.g. CD-R). The portions of data that were not recorded are unable to be reproduced, causing the loss of the data.
If the recording data failed to be record again, it is necessary to record the data to another packet, including the changes to the address of the packet that recorded the data and the change of the location description.